Today I upgraded a dual NT/linux box from RH 6.0 to 6.1. I was concerned
about the effect lilo would have on the NT boot loader, so I elected to
select the packages to upgrade, and deselected all the kernel packages.
When the upgrade continued, it went ahead and installed the kernel packages
anyway and ran lilo, wiping out the NT bootloader on the master boot
record.
(PS how can I get NT booting again?)

The kernel is not something that the user can choose to not upgrade, so . . .
We have removed this selection from the Individual Package Selection screen in
the latest installer. In addition, we have added the Lilo Config screen to the
Upgrade path so that the user can choose where and whether to install Lilo.